1. Field of the Invention
This invention relates to the art of instantaneous tankless water heaters of the general type for domestic use in the home and, especially, for living areas having small kitchens, house trailers, campers, and mobile homes. This invention relates to automatic, electric, in-line water heaters, for the water to be heated is brought into heatabsorbing relation to one or more electrical resistance heating elements and are automatically energized when the water begins to flow.
2. Description of the Prior Art
The Cooksley U.S. Pat. No. 3,968,346 describes a method and apparatus for electrically heating water. This is a compact design having a fast-acting, tankless heater with an elongated tubular casing having the cold water inlet at one side and the hot water and steam outlet at the opposite side. This water heater has two electric heaters, where one may be a rubberized, flexible, heating mat which is surrounded by a thick body of thermal insulation.
The Dannell U.S. Pat. No. 3,969,605 describes a thermal pulse-type heater which is installed within a coolant hose of a liquid-cooled automobile engine. This type of invention is to be used in extremely cold climates for assisting in starting the car early in the morning when the ambient temperature is below zero.
The Youngquist U.S. Pat. No. 4,085,308 describes an electric water heater for use with bathroom showers. Various provisions protect this heater from overheating and burnout under all operating conditions.
The Minier U.S. Pat. No. 2,866,884 relates to electric heaters for bathroom showers. There is a built-in switch control having a manually operated switch button for energizing the heater and a bimetallic switch mechanism serving as an over-temperature protection to deenergize the circuit once the water flow is stopped.
The Rinderspacher et al U.S. Pat. No. 1,805,885 describes a cylindrical hosing having concentric tubes with an electric resistance heater interposed therebetween. The water is compelled to flow in close proximity to the walls of the heating tubes for exchanging the heat from the heater to the water.
The Noland U.S. Pat. No. 4,218,607 describes a water-circulating device for an animal watering apparatus having three nipple valves attached to the water supply tube. There is a heating element that passes in close proximity to the water supply pipe. This design serves to provide an economical mechanism for keeping the animal watering device from freezing in cold weather.
The Cunningham U.S. Pat. No. 4,395,618 describes an electric circulation heater for heating fluid such as oil. There is an imperforate, heavy-duty, steel tubular body closed at both ends and having internal vanes establishing a plurality of separated, longitudinally-extending, chambers therein. The vanes are ported to establish a fluid flow path serially through the chambers. A plurality of metal-sheathed electric heating elements are located within the chambers.
The Knight U.S. Pat. No. 4,459,465 describes an instantaneous fluid heater having a combined safety shutoff and temperature regulator including a hollow heater block with a fluid inlet, a fluid outlet, and inner walls defining a plurality of interconnected heating chambers forming a serpentine fluid flow path from the inlet to the outlet. An electrical sequence switching arrangement cooperates with a plurality of thermostats to sequentially energize the heating elements, beginning with the heating element in the most downstream chamber. The fluid heater includes a flow switch for allowing operation only in response to a minimum fluid flow rate. A safety thermostat is provided at the downstream end of the most downstream chamber to establish a maximum permitted fluid temperature.